This invention relates generally to valves and more particularly to a valve actuating device of a zone heating and/or cooling system which controls a valve for delivering hot or cool fluid to a zone of the system.
In zone heating and/or cooling systems, valves are provided for controlling the flow of heated or cooled fluid (e.g., water or coolant) to the zones they service. One type of valve well-known in the heating and cooling industry is a heat motor type valve which utilizes wax as a pressure medium for opening and closing a valve member. More particularly, wax, in its hardened state, is softened by suitable heating means for moving the valve member of the valve from its closed to its opened position. This type of valve is desirous in circumstances where the valve needs to be opened slowly to prevent water hammer in the system. Water hammer is defined as the change in pressure in closed conduits caused by sudden changes in velocity of flow (e.g., opening or closing a valve too quickly in a system). However, the heat motor valve suffers from the limitation that it takes too long to heat the wax and therefore too long to open and close the valve member. Typically, such a valve takes approximately four minutes to open and six minutes to close. Contractors installing a heating and/or cooling system find the waiting period between the opening and closing of the valve too long to adequately test the valve after it has been installed in the system. Although the performance of such valves is not suspect, this waiting period causes many contractors to avoid using it.
As an alternative to the heat motor type valve, another valve available to contractors is actuated by a solenoid switch which immediately introduces or cuts-off fluid to the system. However, this valve has been known to cause water hammer since it opens and closes the valve too quickly.
Accordingly, among the several objects of the present invention are the provision of a valve actuating device for opening and closing a valve of a zone heating and/or cooling system, the device opening and closing the valve in approximately ten to twelve seconds; the provision of such a device which substantially eliminates water hammer; the provision of such a device which is easy to assemble in that it requires only minimal fasteners and can be assembled by hand and with a screwdriver; the provision of such a device having a linear design which provides strength and durability unlike designs utilizing linkages; the provision of such a device which may be quickly and easily replaced in existing systems; the provision of such a device which has a manual opening feature; the provision of such a device which operates quietly; the provision of such a device which can be applied to valves having large flow capacities; the provision of such a device which can operate on 0.25 amps for a 24 volt motor; the provision of such a device which is compatible with electronic thermostats; and the provision of such a device which is simple in design and economical to manufacture.
In general, the present invention is directed to a valve actuating device for opening and closing a valve connected to an inlet pipe and an outlet pipe of a zone heating and/or cooling system. The valve comprises a valve housing having an inlet which is connected to the inlet pipe, an outlet which is connected to the outlet pipe, a fitting receiving formation with an opening formed therein, and a valve seat disposed between the inlet and the outlet. A valve member, sealingly engagable with the valve seat, is attached to a valve stem which moves the valve member between a closed position in which the valve member sealingly engages the valve seat for blocking the flow of fluid from the inlet to the outlet and an open position in which the valve member is spaced from the valve seat for allowing fluid to pass from the inlet to the outlet. The valve stem is biased by valve stem biasing means to its open position and is extendable through the opening of the fitting receiving formation.
The valve actuating device of the present invention comprises a housing having a fitting which is threadably received by the fitting receiving formation of the valve for securing the housing to the valve. The device further includes an electric motor mounted on the housing, the motor being adapted to drive a shaft having a pinion gear upon its activation for opening the valve. A rack has teeth engagable with the pinion gear of the electric motor and an end portion engagable with the valve stem of the valve. The arrangement is such that the rack is movable upon activation of the motor from a first position in which the end portion of the rack engages the valve stem for maintaining the valve stem in its closed position against the bias of the valve stem biasing means, to a second position in which, upon activation of the motor, the rack is moved via the pinion gear of the motor away from the valve stem thereby enabling the valve stem biasing means to move the valve member to its open position. Means is provided for biasing the rack to its first position. More particularly, the biasing means comprises a cross member integrally formed with an end of the rack opposite the end portion engaging the valve stem, and a plate mounted on the housing. A pair of springs are attached to the cross member and the plate for biasing the rack to its first position.